In general, solar cells have a PN junction. Electrons and holes are generated when the light is incident on the PN junction, the electrons and holes respectively move to a P region and an N region, a potential (electromotive force) is generated between the P region and the N region due to the above phenomenon, and at this time, a current flows when a load is connected to the solar cell.
The solar cells may be broadly classified as one using a silicon semiconductor material and one using a compound semiconductor material. Also, the solar cells using a silicon semiconductor may be classified as crystalline solar cells and amorphous solar cells.
Currently, most of solar cells generally used in a solar power system are silicon semiconductors. In particular, single crystalline and polycrystalline solar cells of a crystalline silicon semiconductor have been widely used due to good conversion efficiency and high reliability.